The goal of the proposed research is development of an efficient and general synthetic approach to a novel family of Tricholomataceae diterpenes. These natural products show potential as new cancer chemotherapeutic agents by virtue of the demonstrated ability of the parent member, lepistal, to induce apoptotic cell death in leukemia and lymphoma cell lines. Synthases of unnatural members of this family would also be valuable in probing the mechanism of lepistal's biological activity and in developing potentially more potent drugs. The synthetic plan proposes as the key transformations, palladium- catalyzed coupling of a cyclopropyltrialkylstannane and an alkenyl iodide to construct a divinylcyclopropane, followed by sigmatropic rearrangement to afford the diterpene core. An extension of the coupling methodology to include stannylepoxides, stannylaziridines, and stannylthioepoxides is also proposed. The specific aims of this proposal are to investigate the aforementioned coupling/rearrangement methodology and to employ it in the synthesis of a series of natural and unnatural Tricholomataceae diterpenes.